Minutes after the bagpipes faded and he took the oath of office on Thursday, Police Commissioner William J. Bratton signaled that he intended to shift the nation’s largest police department away from an aggressive style of patrolling New York City that had alienated many minority residents.

In his first policy message to the city and the police force he now commands, Mr. Bratton said that the tremendous strides the department had made in reducing crime should long ago have given way to fewer confrontational encounters between the police and the public.

“Crime is down to such extraordinarily low levels in this city versus where it was that there is an expectation — or there should be an expectation — that the intrusion of police into citizens’ lives should also diminish,” he told reporters after being sworn in. “But we had the reverse happening.”

A day after he officially took over the department on Wednesday in a private ceremony, Mr. Bratton said it was unfortunate that relations between the police and the community were marked by “disconnect” and “alienation.”

Mr. Bratton’s remarks, often introspective in tone, differed markedly from those of his predecessor, Raymond W. Kelly, who often bristled at the suggestion that his strategies were sowing discord.

“We will all work hard to identify why is it that so many in this city do not feel good about this department that has done so much to make them safe — what has it been about our activities that have made so many alienated?” Mr. Bratton said, speaking to a packed hall at Police Headquarters in Lower Manhattan.

He pledged a new era of policing that would be “a collaboration unlike any that we have ever seen” in New York. “That’s why I came back,” he said.

Mr. Bratton, the city’s 42nd police commissioner, must now deliver on the campaign promises of Mayor Bill de Blasio, who vowed to make changes to the stop-and-frisk tactics that were the dominant theme under Mr. Kelly. But with the Police Department coming under increasing criticism, substantial changes already began taking root toward the end of Mr. Kelly’s tenure, with street stops falling precipitously since early 2012.

Mr. Bratton outlined in the most concrete terms to date how his crime-fighting strategies would differ from those of his predecessor. He singled out Operation Impact, Mr. Kelly’s signature program, which involved sending rookie officers to high-crime neighborhoods to seek out suspicious behavior and confront it. The program led to a soaring number of recorded street stops and angered some residents of neighborhoods such as Brownsville, Brooklyn, who complained of a dragnet approach, particularly in public housing. “The former commissioner, his opinion was that stop, question and frisk and Operation Impact were the way to go,” Mr. Bratton said. “It really is a difference of opinion.”

“I am quite comfortable that we can have less and achieve the same results,” Mr. Bratton said.

Mr. Bratton returns to a department he ran from 1994 to 1996. During that period, he changed the posture of the Police Department from one focused on responding to crimes to one that sought to prevent them, in part through an intense focus on low-level, quality-of-life offenses. Since then, he has spent years consulting departments around the country. He was also the chief of the Los Angeles Police Department.

There he received wide praise as he led a police force that had been plagued by corruption and brutality out from under a federal consent decree in the 2000s. He reached out to the department’s critics early on, and won over most of them by the time he stepped down in 2009, despite a doubling in the number of stop-and-frisk encounters during his tenure.

On Thursday, Mr. Bratton said he would also look to the nation’s other police departments for ideas and inspiration — a striking note of humility for the head of a department that had long seen itself to be the leader in innovation.

Mr. Bratton said returning to Police Headquarters was like coming back to a familiar home that had been remodeled. He said a bottle of Champagne from Mr. Kelly was waiting for him with a note: “Happy New Year, Good Luck.” Mr. Kelly did not attend Thursday’s swearing-in.

While drawing firm distinction with Mr. Kelly, he also offered kind words, saying that under his leadership the Police Department kept the city safe not only from crime but from a terrorist threat that registered far less during Mr. Bratton’s previous tenure. Mr. Bratton’s compliments were in stark contrast to speeches on the day Mr. de Blasio named him as commissioner; neither uttered Mr. Kelly’s name in their prepared remarks.

Mr. Bratton also praised the department’s strategy to suppress violence associated with the informal youth gangs responsible for many of the city’s shootings. Mr. Bratton said he would seek to build on the successes of that program, known as Operation Crew Cut and begun in 2012. He said he would seek to expand it and involve more narcotics officers.

A version of this article appears in print on , on Page A14 of the New York edition with the headline: Bratton Vows to Steer Police Away From Aggressive Tactics. Order Reprints | Today’s Paper | Subscribe